This invention relates to control systems and, more particularly, to a system correlating events among paired variables, and wherein such correlation is retained for varying retention times depending on the course of successive events.
Control systems are widely used today in a broad class of physical systems ranging from the control of elevators to the pumping of oil, in the control of chemical processes, and in electronic systems such as radar and communications. Research is being conducted for the implementation of control in biological systems. Increased versatility for the control systems is attained by the introduction of programmable features such as those associated with the use of a computer as a component of the control system. Thereby, the operation of the system can be altered as required by a specific situation by a corresponding change in the computer program. Incrased capability for the control systems is attained by the introduction of adaptive features such as may be found, for example, in an adaptive radar antenna wherein the response of the antenna is made to vary in accordance with the characteristics of a signal incident upon the antenna. Yet another feature which has been studied in systems having a "learning" capability is a self-programmable feature wherein the program can be varied in accordance with measured changes in input variables to the system.
By the use of the foregoing features, control systems can be constructed with increased versatility and capacity for handling situations of ever increasing complexity. But, such capability is attained at a cost, namely, with increased capability there is a corresponding increase in the complexity and expense of the equipment of the control system.
A problem arises in that there are many situations in which there is no room for complex, bulky and heavy equipment. Thus, the foregoing control systems incorporating the adaptive and self-programmatic features would not be suitable in a health care device wherein such a system is to be worn by a person for the control of a bodily function. And even in situations wherein there may be room for such equipment, the expense both in terms of money and in terms of the engineering manpower required to operate the equipment militates against the use of the foregoing control systems.
A further problem arises in the case of programmed equipment for use in the care of physiological phenomena in human patients. Due to individual variations among people, a program adapted for use with one patient has been found to be substantially inoperative with respect to other patients.